Microbial production and biocatalytic docking of pectin lyase for green oil extraction in biorefinery applications.

Solid‑state fermentation was optimized using Aspergillus niger ISL‑09 and Bacillus subtilis 01‑21 with orange peel as substrate for pectin lyase production. The optimal conditions were: substrate level 10 g, moisture content 25 mL for A. niger and 5 mL for B. subtilis, inoculum size 10%, and incubation times of 72 h and 48 h, respectively. These conditions gave enzyme activities of 2.45 U/mL (A. niger) and 1.61 U/mL (B. subtilis). Partial purification by 80% ammonium sulfate precipitation followed by dialysis increased specific activities to 7.4 U/mg and 7.0 U/mg, with recovery yields of 76.13% and 70.24%, respectively. Enzyme characterization showed optimal activity at 60 °C (pH 8.0) for A. niger and 50 °C (pH 8.5) for B. subtilis. SDS and EDTA enhanced activity at 2.5 mM and 2.0 mM, respectively. Both enzymes retained substantial activity for up to 30 min before declining due to thermal or temporal denaturation. When applied to in situ corn‑oil extraction, the enzymes outperformed untreated controls, achieving extraction yields of 15.2% (A. niger) and 10.72% (B. subtilis). In‑silico docking of modeled 3D structures identified key catalytic residues Asp154, Arg176, and Arg236 in A. niger pectin lyase that bind galacturonic acid. PatchDock simulations showed favorable ligand‑enzyme interactions and stable clustering, supporting high catalytic potential. This integrated approach demonstrates the feasibility of using microbial pectin lyase for sustainable, cost‑effective oil extraction, offering both experimental and molecular insights for future biocatalyst development in biorefinery platforms.